Decoding apparatus and method therefor

ABSTRACT

A decoding apparatus adapted for an optical access system comprises an interface, a detection element, and an error correction element. The interface receives a data from an optical storage medium. The detection element executes an error detection on the data received from the interface before the data is buffered to a first memory and generates a defect result in response to the error detection. The error correction element decodes the data in response to the defect result. A decoding method for an optical access system comprising the steps of: receiving a data from an optical storage medium via an interface of the optical access system; executing an error detection on the data received from the interface before the data is buffered to a first memory; generating a defect result in response to the error detection; and decoding the data in response to the defect result.

CROSS-REFERENCES TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a decoding apparatus adapted for anoptical access system and a method therefor; more particularly, relatesto a decoding apparatus and a decoding method for detecting andcorrecting errors in a data retrieved from an optical storage medium.

2. Descriptions of the Related Art

Since optical storage media have advantages of large capacity, low cost,high access speed, high compatibility, and portability, they become oneof the most popular devices for storing data nowadays.

Due to the influence of scratches, fingerprints, collision, or dust,errors might occur when data stored in an optical storage medium isretrieved. Therefore, optical access systems of the prior art usuallyhave a correction mechanism to correct the errors. FIG. 1 shows anoptical access system of the prior art, and FIG. 2 shows a flow chart ofa method of the prior art adapted for the optical access system tocorrect errors. The optical access system 1 comprises a pickup head 105,a buffer 107, a DRAM 109, a DRAM controller 111, a detection element113, and an error correction element 115. The optical access system 1retrieves data from an optical storage medium 101, such as a compactdisc, and decodes the data before transmitting the data to a host 103which is electrically connected to the optical access system 1. Moreparticularly, referring to both FIG. 1 and FIG. 2, a pickup head 105reads the data from the optical storage medium 101 in step 201. Thenstep 203 is executed wherein the data is stored in the buffer 107temporarily. In step 205, the data is then written into the DRAM 109from the buffer 107 through the DRAM controller 111. Step 207 isexecuted to transmit the data from the DRAM 109 through the DRAMcontroller 111 to the detection element 113 to detect whether an errorin the data exists after decoding the data. If no, it means that thereis no error detected in the data and step 215 is executed to transmitthe data to the host 103. If yes, step 209 is executed in which the datais then transmitted to the error correction element 115 to be corrected.After step 209 is executed, the method goes to step 211 to store acorrected data back to the DRAM 109. Finally, step 213 is executedwherein the corrected data is transmitted to the host 103.

In step 207, the decoding and detecting comprise an error detection code(EDC) check and at least one of a syndrome check and an erasure check toaffirm whether an EDC error, a syndrome error, or an erasure error ofthe data exists.

U.S. Pat. No. 6,003,151 and U.S. Pat. No. 6,662,335 disclose similarsystems or methods shown in FIG. 1 and FIG. 2. In both of the twopatents, data is stored in a memory through a memory controller first.Then the data is transmitted to be detected whether there is an error inthe data. If yes, the data and the error are sent to an error correctionelement for correct the error. After the correction, the corrected datais transmitted to a host. Based on the above descriptions, peopleskilled in the art can realize that the memory, i.e., the DRAM 109 isfrequently accessed. This occupies lots of the bandwidth of the memory.Besides, if there is no error in the data, the process of decoding isstill executed, which influences process speed and wastes power.Especially for BD/DVD/HDDVD discs, an error rate of data is generallyless than 1%. In other words, over 99% of the decoding is unnecessary.

To solve the aforementioned drawbacks, a decoding apparatus which maydecrease unnecessary operations and save the bandwidth of memory isrequired in the industrial field.

SUMMARY OF THE INVENTION

An object of this invention is to provide a decoding apparatus adaptedfor an optical access system. The decoding apparatus comprises a firstmemory, an interface, a detection element, and an error correctionelement. The interface is configured to receive a data from an opticalstorage medium. The detection element is configured to execute an errordetection on the data received from the interface before the data isbuffered to the first memory and to generate a defect result in responseto the error detection. The error correction element is configured todecode the data if the defect result represents that there is an errordetected. The error detection comprises an error detection code (EDC)check and at least one of a syndrome check and an erasure check.

Another object of this invention is to provide a decoding apparatusadapted for an optical access system. The decoding apparatus comprises afirst memory, an interface, a detection element, and an error correctionelement. The interface is configured to receive a data from a Blu-raydisc. The detection element is configured to execute an error detectionon the data from the interface before the data is buffered to the firstmemory and to generate a defect result in response to the errordetection. The error correction element is configured to decode the dataif the defect result represents that there is an error detected. Theerror detection comprises at least one of an error detection code (EDC)check, a syndrome check and an erasure check.

Another object of this invention is to provide a decoding method for anoptical access system. The decoding method comprises the following stepsof: receiving a data from an optical storage medium via an interface ofthe optical access system; executing an error detection on the datareceived from the interface before the data is buffered to a firstmemory; generating a defect result in response to the error detection;and decoding the data if the defect result represents that there is anerror detected. The error detection comprises an error detection code(EDC) check and at least one of a syndrome check and an erasure check.

Another object of this invention is to provide a decoding method for anoptical access system. The decoding method comprises the steps of:receiving a data from a Blu-ray disc via an interface of the opticalaccess system; executing an error detection on the data from theinterface before the data is buffered to a first memory; generating adefect result in response to the error detection; and decoding the dataif the defect result represents that there is an error detected. Theerror detection comprises at least one of an error detection code (EDC)check, a syndrome check and an erasure check.

The present invention determines if there is an error in a data beforethe data is buffered into a memory. The present invention decodes thedata only when there is an error in the data. This invention simplifiesthe procedure of decoding; therefore, saves the bandwidth of memory andpower.

The detailed technology and preferred embodiments implemented for thesubject invention are described in the following paragraphs accompanyingthe appended drawings for people skilled in this field to wellappreciate the features of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a conventional optical access system;

FIG. 2 shows a flow chart of detecting and correcting errors of theprior art;

FIG. 3 shows a block diagram of a first embodiment in accordance withthe present invention;

FIG. 4 shows a flow chart of a second embodiment in accordance with thepresent invention;

FIG. 5 shows a block diagram of a third embodiment in accordance withthe present invention; and

FIG. 6 shows a flow chart of a fourth embodiment in accordance with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A first embodiment of the present invention is a decoding apparatus,adapted for an access storage system, for decoding data effectively. Inthis embodiment, the optical access system, as illustrated in FIG. 3,may access data on an optical storage medium in a CD format, a DVDformat, a Blu-Ray format or a HD-DVD format. The decoding apparatus 3comprises a pickup head 301, an interface 303, a first memory 305, asecond memory 307, a detection element 309, and an error correctionelement 311. The pickup head 301 is configured to read a data 302 fromthe optical storage medium (not shown). The interface 303 receives thedata 302 through the pickup head 301, and demodulates the data 302.After demodulation, a demodulated data 304 is transmitted to thedetection element 309 and buffered to the first memory 305. Thedetection element 309 executes an error detection on the demodulateddata 304 received from the interface 303 before the demodulated data 304is buffered to the first memory 305. The error detection comprises anerror detection code (EDC) check and at least one of a syndrome checkand an erasure check to find whether any EDC error, syndrome error, orerasure error exists in the demodulated data 304. Then the detectionelement 309 generates a defect result 306 in response to the errordetection, and stores the defect result 306 in the second memory 307.The error correction element 311 retrieves the defect result 306 fromthe second memory 307. If the defect result 306 represents that there isan error detected, the error correction element 311 decodes thedemodulated data 304. If the defect result 306 indicates that there isno error detected, the error correction element omits the decoding,i.e., an error correction is unnecessary to be run and the errorcorrection element 311 waits for retrieving a next defect result. Duringthe decoding, the error correction element 311 starts the errorcorrection by retrieving the demodulated data 304 from the first memory305, and decoding the demodulated data 304 in response to the defectresult 306 from the second memory 307. The error in the demodulated data304 is corrected thereby.

In this embodiment, the first memory 305 and the second memory 307 maybe one part of a memory respectively, or independent from each other.

A second embodiment of the present invention is a decoding methodadapted for an optical access system, such as recited in the firstembodiment, which may access data on an optical storage medium in a CDformat, a DVD format, a Blu-Ray format or a HD-DVD format. FIG. 4 showsa flow chart of the method. In step 401, receiving a data from anoptical storage medium via an interface of the optical access system isexecuted. In step 403, demodulating the data is executed. Afterdemodulation, step 405 is executed to execute an error detection on thedemodulated data received from the interface before the demodulated datais buffered to a first memory. Step 407 is then executed to generate adefect result in response to the error detection, and the defect resultis stored in a second memory. After the defect result is generated, thedemodulated data is buffered to the first memory in step 409. Step 411is then executed to determine whether the defect result represents thatthere is an error detected in the demodulated data. If no, the decodingmethod omits the decoding and goes to step 415 wherein the method isfinished. Otherwise, the decoding method goes to step 413 to decode andcorrect the demodulated data by retrieving the demodulated data from thesecond memory. After step 413 is executed, the error in the demodulateddata is corrected and the decoding method goes to step 415 wherein themethod is finished.

Similar, the error detection in step 405 comprises an EDC check and atleast one of a syndrome check and an erasure check to find whether anyEDC error, syndrome error, or erasure error exists in the data.

In addition to the steps shown in FIG. 4, the second embodiment is ableto execute all of the operations or functions recited in the firstembodiment.

A third embodiment of the present invention is a decoding apparatus,adapted for an optical access system, for decoding data effectively. Inthis embodiment, the optical access system, as illustrated in FIG. 5,may access a data on an optical storage medium in a Blu-ray format,e.g., a Blu-ray disc. The decoding apparatus 5, disposed in the opticalaccess system, comprises a pickup head 501, an interface 503, a firstmemory 505, a second memory 507, a detection element 509, and an errorcorrection element 511. The pickup head 501 reads data from the Blu-raydisc (not shown). The interface 503 receives the data 502 through thepickup head 501, and demodulates the data 502. After demodulation, ademodulated data 504 is transmitted to the detection element 509 andbuffered in the first memory 505. The detection element 509 executes anerror detection on the demodulated data 504 received from the interface503 before the demodulated data 504 is buffered to the first memory 505.The error detection comprises an EDC check and at least one of a burstindicating subcode (BIS) syndrome check, a long distance code (LDC)syndrome check, and an erasure check to find whether any EDC error, BISerror, LDC error, or an erasure error exists in the demodulated data504. Then the detection element 509 generates a defect result 506 inresponse to the error detection, and stores the defect result 506 in thesecond memory 507. The error correction element 511 retrieves the defectresult 506 from the second memory 507. If the defect result 506indicates that there is no error detected, the error correction element511 executes a simplified decoding procedure to affirm the defect result506 or omits the decoding directly. If the defect result 506 indicatesthat there is some error detected, the error correction element 511starts the error correction by retrieving the demodulated data 504 fromthe first memory 505, and decoding the demodulated data 504 if thedefect result 506 represents that there is an error detected. During thedecoding, the error in the demodulated data 504 is corrected.

More particularly, the error correction element 511 comprises a BISerror decoding element 511A and a LDC error decoding element 511B for aBlu-Ray access system. The BIS error decoding element 511A is configuredto execute a BIS decoding, i.e., to decode and correct BIS errors in thedemodulated data 504. The LDC error decoding element 511B is configuredto execute a LDC decoding, i.e., to decode and correct LDC errors in thedemodulated data 504. If the detection element 509 detects no error, theBIS error decoding element 511A may be used to affirm the defect result506. If the BIS error decoding element 511A is not activated when thedetection element 509 detects no error, the decoding apparatus 5 treatsthat no error exists so the error correction is not run. If the BISerror decoding element 511A is activated in such a circumstance, the BISerror decoding element 511A reads demodulated data 504 from first memory505 and executes the BIS decoding to check if any error can be found. Ifboth of the detection element 509 and the BIS error decoding element511A find no error, the error correction is unnecessary to be run. Ifthe BIS error decoding element 511A detects at least an error during theBIS decoding, error information 508 would be sent to the LDC errordecoding element 511B. Then the LDC error decoding element 511B isactivated to execute the LDC decoding to correct the error.

A unit of the LDC decoding may be one of a cluster, a sector, and asyndrome according to the defect result 506 and/or the BIS decoding.

In this embodiment, the first memory 505 and the second memory 507 maybe one part of a memory respectively, or independent from each other.

A fourth embodiment of the present invention is a decoding methodadapted for an optical access system, such as recited in the thirdembodiment, which may access data on an optical storage medium in aBlu-ray format. FIG. 6 shows a flow chart of the method. In step 601, adata is received from the optical storage medium, for example, a Blu-raydisc via an interface of the optical access system. In step 603,demodulating the data is executed. Then step 605 is executed in which anerror detection is executed on the demodulated data received from theinterface, before the demodulated data is buffered to a first memory, todetect if there is an error in the demodulated data. In particular, theerror detection comprises an EDC check, a LDC syndrome check, a BISsyndrome check, a syndrome check, and an erasure check. Then step 607 isexecuted to generate a defect result in response to the error detection,and the defect result is stored in a second memory. Afterward, thedemodulated data is buffered to the first memory in step 609. Then step611 is executed to determine if the defect result represents that thereis an error in the demodulated data. If yes, step 613 is executed toexecute BIS decoding to affirm the defect result. Otherwise, step 615 isexecuted to determine whether the BIS decoding is activated. If no, thedecoding method goes to step 621 wherein the method is finished. If yes,step 613 is executed. After step 613 is executed, the decoding methodgoes to step 617 to check whether one of the BIS decoding and the defectresult indicates that there is an error in the demodulated data. If no,the method goes to step 621 wherein the method is finished. Otherwise,the method goes to step 619 wherein LDC decoding is executed byretrieving the demodulated data from the first memory. After the LDCdecoding is finished, the demodulated data in the first memory iscorrected and the method goes to step 621 wherein the method is finished

Similar, the error detection in step 605 comprises an EDC check, a LDCsyndrome check, a BIS syndrome check, a syndrome check, and an erasurecheck to find whether any error exists in the data.

In addition to the steps shown in FIG. 6, the fourth embodiment is ableto execute all of the operations or functions recited in the thirdembodiment.

The above disclosure is related to the detailed technical contents andinventive features thereof. People skilled in this field may proceedwith a variety of modifications and replacements based on thedisclosures and suggestions of the invention as described withoutdeparting from the characteristics thereof. Nevertheless, although suchmodifications and replacements are not fully disclosed in the abovedescriptions, they have substantially been covered in the followingclaims as appended.

1. A decoding apparatus adapted for an optical access system,comprising: a first memory; an interface for receiving a data from anoptical storage medium; a detection element for executing an errordetection on the data received from the interface before the data isbuffered to the first memory and for generating a defect result inresponse to the error detection; and an error correction element fordecoding the data if the defect result represents that there is an errordetected; wherein the error detection comprises an error detection code(EDC) check and at least one of a syndrome check and an erasure check.2. The decoding apparatus as claimed in claim 1, wherein if the defectresult represents that no error is detected in the data, the errorcorrection element omitting the decoding.
 3. The decoding apparatus asclaimed in claim 1, further comprising: a second memory for storing thedefect result; wherein the error correction element retrieves the datafrom the first memory and retrieves the defect result from the secondmemory.
 4. The decoding apparatus as claimed in claim 3, wherein thefirst memory and the second memory are one part of a memoryrespectively.
 5. The decoding apparatus as claimed in claim 3, whereinthe first memory is independent from the second memory.
 6. The decodingapparatus as claimed in claim 1, further comprising a pickup head forreading the data from the optical storage medium.
 7. A decodingapparatus adapted for an optical access system, comprising: a firstmemory; an interface for receiving a data from a Blu-ray disc; adetection element for executing an error detection on the data from theinterface before the data is buffered to the first memory and forgenerating a defect result in response to the error detection; and anerror correction element for decoding the data if the defect resultrepresents that there is an error detected; wherein the error detectioncomprises at least one of an error detection code (EDC) check, asyndrome check and an erasure check.
 8. The decoding apparatus asclaimed in claim 7, wherein the error correction element uses one ofburst indicator subcode (BIS) decoding and long distance code (LDC)decoding to decode the data.
 9. The decoding apparatus as claimed inclaim 8, wherein if the detection element detects no error, the errorcorrection element executes the BIS decoding to affirm the defectresult.
 10. The decoding apparatus as claimed in claim 9, wherein if thedetection element detects no error but the error correction elementdetects an error during the BIS decoding, the error correction elementfurther executes the LDC decoding to affirm the error.
 11. The decodingapparatus as claimed in claim 8, wherein a unit of the LDC decoding isdetermined to be one of a cluster, a sector, and a syndrome according toone of the defect result and the BIS decoding.
 12. A decoding method foran optical access system, comprising: receiving a data from an opticalstorage medium via an interface of the optical access system; executingan error detection on the data received from the interface before thedata is buffered to a first memory; generating a defect result inresponse to the error detection; and decoding the data if the defectresult represents that there is an error detected; wherein the errordetection comprises an error detection code (EDC) check and at least oneof a syndrome check and an erasure check.
 13. The decoding method asclaimed in claim 12, wherein if the defect result represents that noerror is detected in the data, the decoding step is omitted.
 14. Thedecoding method as claimed in claim 12, further comprising the step of:storing the defect result in a second memory; wherein the decoding stepcomprises the steps of: retrieving the data from the first memory; andretrieving the defect result from the second memory.
 15. A decodingmethod for an optical access system, comprising the steps of: receivinga data from a Blu-ray disc via an interface of the optical accesssystem; executing an error detection on the data from the interfacebefore the data is buffered to a first memory; generating a defectresult in response to the error detection; and decoding the data if thedefect result represents that there is an error detected; wherein theerror detection comprises at least one of an error detection code (EDC)check, a syndrome check and an erasure check.
 16. The decoding method asclaimed in claim 15, wherein the decoding step uses one of BIS decodingand LDC decoding to decode the data.
 17. The decoding method as claimedin claim 16, wherein if the defect result indicates no error, thedecoding step uses the BIS decoding to affirm the defect result.
 18. Thedecoding method as claimed in claim 17, wherein if the defect resultindicates no error but the BIS decoding indicates an error, the decodingstep further executes the LDC decoding to affirm the error.
 19. Thedecoding method as claimed in claim 16, wherein a unit of the LDCdecoding is determined to be one of a cluster, a sector, and a syndromeaccording to one of the defect result and the BIS decoding.